To further evaluate the role of P2X1 in sustaining LIC activities, we performed a serial transplantation with P2x1-null AML cells and revealed that the immunophenotypic Mac-1+c-Kit+P2x1-null LIC frequency was notably decreased to 30.7% or 13.1% of WT LICs upon primary (Fig. 2A, B) or secondary transplantation (Fig. 2C), respectively. This evidence concerns the gene P2RX1 and acute myeloid leukemia.